Machine for stretching metals



April 6, 1943. N. c. LAKE MACHINE FOR STRETCHING METALS 4 Sheets-Sheet 1Filed June 24, 1941 April 6, 1943. N. c. LAKE MACHiNE FOR STRETQHINGMETALS Filed Jun'e 24, 1941- 4 sheets-sheet 2 AApril 6, 1943. N. c. LAKEf 2,315,971

`MA\GHINE FOR STRETCHING METALS 'Filed June 24, 1941 4 sheets-Sheet s ,Md 1f La o 'ff ."o'

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Aprile, 1943.

N. LAK 2,315,971

` MACHINE FOR STRETGHING METALS FildJune 24, 194i 4 sheets-sheet 4 .fIII/IA Patented Apr. 6, 1943 UNET MACHINE FOR STRETCHING METALS NormanCecil Lake, Stockton-on-Tees, England,

assignor to Head, Wrightson & Company, Limited, Thornaby-on-Tees,England Application June 24, 1941, Serial No. 399,546 In Great BritainNovember 13, 1939 6 Claims.

This invention relates to stretching machines such as are commonlyemployed to straighten and/or remove twists in extruded non-ferroussections, particularly aluminium.

In carrying out the present invention a stretching machine comprises incombination a pair of gripper heads, gripper jaws on the heads to gripmaterial, the heads being relatively movable to stretch material grippedbetween them and a frame to which the stretching load is transmittedfrom the heads, the frame being a structure which is self-contained toresist the stretching load and including longitudinal members spacedapart to receive the heads between them and engaged directly by theheads so that the load due to a stretching operation is transmitted fromthe heads to the longitudinal members as a compressional load at zoneswhich are diametrically opposed about the stretching axis between theheads; the frame also includes transverse jaw or C- shaped parts whichare connected to the longitudinal members at their outer jaw ends andare all located at the same side of the frame,` these jaw shaped memberssupporting the longitudinal members against buckling under the compres-Vsional load.

Preferably two longitudinal members are employed these members beingdiametrically opposed about the stretching axis between the two heads.Since load is transmitted to the longitudinal members at zones which arediametrically opposed about the stretching axis, stresses which would beproduced by eccentric loading of the frame are avoided and this enablesthe frame to be of a comparatively light construction. The fact alsothat the longitudinal members are subjected, during a stretchingoperation, to a cornpressional load and that the tendency of thelongitudinal members to buckle under this compressional load isprevented by the jaw shaped members enables a frame to be provided whichis selfcontained, i. e. it does not rely upon any external structure. Inaddition since the load is taken directly from the heads to the framemembers the heads can be mounted on large ball or roller bearing wheelsthe axles of which are subjected to little or no pressure. By locatingthe jaw shaped parts all at the same side of the machine, the structureis rendered capable of easy access for the operator.

A further feature of the invention relates to means whereby a gripperhead of a stretching machine is connected to a frame so that the loaddue to a stretching operation is transmitted from the head-to the frameto be absorbed thereby'.

According to this feature of the invention the connecting means includesapin or its equivalent which enables the head to swivel about an axistransverse to the stretching axis so that this head is enabled to beself-aligning in the frame.

The invention is illustrated in the accompanying drawings in whichFigure 1 and la is a front elevation and Figurej2, 2a, a plan of astretching machine; Veach of these figures is in two partswhichrespectively continue on from 'one another at the lines I-I andII-II; Figure y3 is an end elevation 'looking in the direction of thearrow III Figure 1, Figure 4 isla longitudinal section of one of theheads, Figure 5 a plan View of the head and Figure 6 an end elevationthereof. l Figure 7 is a longitudinal section through a cylinder backstop mechanism.

Referring to the accompanying drawings, the machine comprises a `mainframe having spaced longitudinal mem-bers Cf'and lgripper heads A and Bof which the head B-is what maybe ytermed the fixed head and the head Athe moving head. Each head is supported by large diameter ball or rollerbearing wheels -D, -thetrack for -which is provided by the lowerlongitudinal member of the frame. H or other section beams may be usedfor the extension tracksl-as shown lat X. Each head is Yprovided withgripper jaws EE which may `be operated in the manner hereinafterdescribed. Y

The head B at the end remote from its gripping jaws EE is formed with aYtransverse cylindrical boss E which extends from one side to the otherof the longitudinal load line, or Astretching axis between the heads A,B the -axis of the boss E cuttingV this load line. The outer ends ofthis bossrE which are spaced e-qui-distantly from the load line, haveonly a small clearance between plane longitudinal faces C formed on thelongitudinal bed frame ymembers C it being understood that the faces Coppose one another from diametrically opposite -sides of the load lineof the head. v

To enable this head` to be secured in different positions depending oriythe lengths of sections to be straightened, the boss E -is Abored andcounter-bored from its opposite ends, as is shown in Figure 4, eachAbore Tand counter-bore receiving a large diameter `cylindrical lockingpin AA formed centrally of its ends with a collar BB vreceived in thecounterfbore; this collar` is arranged to constitute a piston vbyproviding it with cup leathers ,and packing and the counter-bore beyondthis collar vis closed by a bush CC or other suitable means ofsealingthroughWhich the out.

er end of the pin AA passes. Hence, by admitting air or other fluidunder pressure to one side of the pistons or the other, the pins AA areforced inwardly or outwardly of the boss. Each of the plane longitudinalfaces C of the bed longitudinal members is formed with a plurality oflongitudinally spaced holes'F to receive accurately the locking pins AAand thus, by withdrawing the pins AA into the boss E, the head B can bemoved longitudinally on the track to the required a slight eccentricityof loading, due to sectionsv not being centrally disposed in the gripperjaws to an -absolute minimum, since the gripper head B will be able toswivel on these pins AA and4 thus align itself up with the other head.

This gripper head B may be adjusted from one position to another bymeans of-a motor driven winch G around the drum of which' passes awire-rope H, the two ends of the rope being secured at H', H2 to theframe of the head B and the rope passing over a return pulley H3 and 'a'guide pulley H4 so that when the winch is driven in one or otherdirection the head Bis correspondingly moved in one or other direction.Control of this arrangement is effected -by push-button switches locatedat different points on the machine.

'Ihe other head A is arranged to be moved hydraulioally to effect thestretching operation; for this purpose this head is connected at its endremote fromthegripper-jaws EE, to two pull rods J connected to a crosshead K lwhich bearsV against the outer end of a ram L workingfin acylinder lM, which extends backwardly between the pull rods. Thiscylinder M is formed with a transverse enlargement or wing N one onleach side of and diametrically opposed about thecentre line of loadingof this head, this centre Vline being of course in line with theequivalent line of the other head; these two wings, which are of equalradial length, fit accurately between the longitudinal faces C on thebed longitudinal' members already referred to,y the outer ends of thewings have plane faces which abut faces on the end of the longitudinalmembers and the wings are secured by bolts to the longitudinal members Cso as to secure the cylinder in position, it being understood that theplane faces O on .the enlargements are in line with one another. j

When now pressure liquid is admitted to the ram L, this head A iscaused, through the. pull rods J to be moved away from the other head Bso producing a stretching or straightening operation on a sectiongripped by the two heads A and B.

It may now be pointed out that the function of the cylindrical boss E onthe one head B and that of thetransverse enlargements N on the ,t

ranged about the load centre line or axis between the two heads, soavoiding any diiculties due to eccentric loading. It will also beapparent that the cylinder M acts as a spacer between the bedlongitudinal members C and in addition imparts lateral stiifness to theframe.

As the ram L would be required to have a long stroke the crosshead K mayif desired be supported by a roller P running on a track Q formed ofrolled steel joist or other suitable material. In order to return themoving gripper head A, a return ram R wiuld be provided, this ramworking in a cylinder S formed in the rst ram L.

The bed frame longitudinal members C are formed by two channel or Tshaped members running the full length of the machine and formed offabricated steel or cast construction,

preferably a fabricated steel construction. It will be apparent thatduring a stretching operation, the stretching load between the heads istransmitted to the longitudinal members C as a compressive load; thesetwo members are supported-at frequent intervals by heavy steel plates orbrackets U, so designed that they support'the members against theirtendency to buckle under the compressive load from the stretchingoperation. The result of this arrangement is that the frame comprised`of the longitudinal members C and the brackets U is one which isself-contained against the loads due to la stretching operation,

i. e., the frame is independent of any external structure and the weightof the section is considerably reduced.

As shown, 'thebed members C are disposed about a vertical axis but theymay be aboutan inclined axis, i. e., so `that the parallel faces C' ofthe longitudinal members C engaged by the outer ends of the cylindricalboss E or by the outer ends of the extension N on the cylinder M, are atright angles to a plane which passes at an angle to the horizontalthrough the longitudinal load line.

The arrangement may be modified to suit local conditionsbut for smallsections which can easily be handled by men, these longitudinal membersmight well be arranged about a Vertical axis which arrangement wouldgive complete freedom of access on both sides of the machine. Dependingon the sizeof theV machine, the distance from one side ofthe machine tosections in the machine for stretching may be kept small enough to givereasonable access, but in any case no matter what size of machine isrequired free access can be Vobtained from the other side. The operatormay stand on the floor level at the base of the supporting frames or onsome small stool,

` and in this case the section will be at normal height for the averageAman to adjust, and there will be clearance for the mans head beneaththe main plate of the upper longitudinal member C. 1n this case of aAvertical axis, the sections can be handled into the machine by means ofa special C shapedlftinghook.v

With this arrangement there is'much greater freedom of access to bothsides of the machine, due to the fact that the operator has to negotiateonly half the width of longitudinal members in order to reach to thecentre line of the machine.

The track for the head B may be extended as shown at X at one end tofacilitate maintaining the adjustable gripper head, particularly thepistons and gripper jaws of that head.

In Figures 4 and 5 is shown a convenient mechanisrn for operating thegripper jaws of the head B, it being understood that a similar mechanismwould be provided for the gripper jaws of the other head A. The jaws areoperated through links from an hydraulic or pneumatic ram and cylinderarrangement DD and one or more of these arrangements may as' is shown inFigure 7 be provided with an adjustable stop FF, so as to limit thetravel of the appropriate gripper blocks in order that sections may bemounted on these gripper blocks and set up in a position almostcorresponding to the position in which the section will be finallygripped As a further aid in this respect, a roller V may be providedopposite one or more of the gripper blocks tc support the section beforeand after gripping, that is, when the gripper blocks are withdrawn.These rollers V should preferably be mounted on a dashpot W containing aexible pressure medium, such as compressed air, so that whilst thesection is being stretched any projection of the section below the levelof the gripper jaws will depress the roller so as to avoid distortion ofthe section.

It will be apparent that with the construction of frame referred to,that is a frame comprising the longitudinal members and the transverseC-shaped members, that the gripper heads in the frame can be completelywithdrawn from the frame through the open end this being a feature ofsome importance for the purpose of maintenance.

What I claimis:

1. A stretching machine comprising in combination a pair of gripperheads, gripper jaws on the heads to grip material to be stretchedbetween the heads, means to move the heads relatively apart to stretchmaterial gripped by the heads, and a frame to which the stretching loadis transmitted from the heads, the frame being a structure which isself-contained to resist the load and the frame including a pair ofopposed longitudinal members spaced apart to receive the heads betweenthem and engaged directly by the heads so that the load due to astretching operation is transmitted from the heads to the longitudinalmembers as a compressional load at zones which are diametrically opposedabout the stretching axis between the heads and the frame including alsoa plurality of transverse open jaw-shaped parts connected at their jawextremities respectively to the longitudinal members to support themagainst buckling under the compressional load, all the jaw shaped partsbeing located at the same side of the longitudinal members with the jawopenings facing the longitudinal members to provide ready access to theheads from the other side of the longitudinal members.

2. A stretching machine comprising in combination a pair of gripperheads, gripper jaws on the heads to grip material to be stretched, meansto move at least one of the heads away from the other to stretchmaterial gripped between the heads, a frame including a pair oflongitudinal members providing opposed surfaces and means connecting theheads to the frame so that the stretching load is transmitted from'theheads to the frame, the said connecting means for at least one of theheads including a pair of opposed pins located at the trailing end ofthe gripper jaws, the said pins constituting pivots enabling the head toswivel to align itself.

3. A stretching machine comprising in combination a pair of gripperheads, gripper jaws on the heads to grip material to be stretched, aframe including longitudinal members having opposed pairs of aperturesand spaced transverse open jaw shaped members, the said members beingconnected respectively at their jaw ends to the' longitudinal membersand being arranged at the same side of the machine with the jaw openingsfacing said longitudinal members, power means to move one of the headsaway from thecther, the

said power means reacting on the frame and means to locate the otherhead at different positions along the length of the longitudinalmembers, the said locating means including a pair of opposed pinscarried by the head at the ytrailing end of the gripper jaws, and meansto move the pins into different pairs of apertures in the longitudinalmembers.

4. A stretching machine comprising in combination a pair of gripperheads, gripper jaws on the heads to grip material to be stretched, aframe including a pair of opposed longitudinal members and a pluralityof spaced transverse open jaw shaped members, the said members beingconnected at their outer jaw ends respectively to the longitudinalmembers and being arranged at the same side of the machine with the jawopenings facing said longitudinal members to provide ready access to theheads from the other side of the longitudinal members, a frame componentinterposed between the said longitudinal members, the said componentproviding a power means to move one head away from the other to stretchmaterial gripped between the heads, and means to connect the other headin spaced relation from the first head to the longitudinal members sothat the stretching load is transmitted from the heads to thelongitudinal members as a compressional load, the transverse jaw memberssupporting the longitudinal members against buckling under thecompressional load.

5. A stretching machine comprising in combination a frame having twospaced parallel longitudinal members providing two faces opposed to oneanother the said faces having a series of apertures arranged in opposedpairs, a pair of gripper heads, gripper jaws on said heads to gripmaterial to be stretched, a ram and cylinder arrangement, extensions onone part of the arrangement which extend between the two faces, meansconnecting the said extensions to the longitudinal members, connectionsfrom the other part of the arrangement to one of the heads whereby thehead can be moved away from the other head to effect a stretchingoperation, a pair of opposed cylindrical pins on the other head, meansto thrust the pins into any one of a pair of the series of apertures inthe opposed faces of the longitudinal members, the two heads thusimposing a compressional load on the two longitudinal members of thefra-me during a stretching operation, and spaced transverse C-shapedmembers connected at their outer limb ends to the longitudinal membersto support them against buckling under the compressional load, the saidC members being all arranged at the same side of the longitudinalmembers.

v6. A stretching machine comprising in combination a frame having twospaced parallel longitudinal members providing two faces opposed to oneanother, the faces having series of apertures arranged in opposed pairs,a pair of gripper heads, gripper jaws on said heads to grip material tobe stretched, a ram and cylinder arrangement, extensions on one part ofthe arrangement which extend between the two faces, means securing thesaid extensions to the longitudinal members, connections from the otherpart of the arrangement to one of the heads whereby the head can bemoved away from the other head to effect a stretching operation, a pairof opposed cylindrical pins on the other head, ram and cylinder means tothrust the pins into any one of a pair of the series of apertures in theopposed faces of the longitudinal members, the two heads thus imposinga, compressional load on the two longitudinal members of the frameduring a stretching operation, and spaced transverse C- shaped membersconnected at their outer limb ends to the longitudinal members tosupport'l them against buckling under the compressional load, the said Gmembers being all arranged at the same side of the longitudinal members.

NORMAN CECIL LAKE.

